Chapter 1: Our steep clay-tiled roof in Crondall has tiles slipping out of line. Can it be repaired, or does it all need redoing?
What we find
A steep pitch sheds water fast, but gravity also pulls on every tile. On the older cottages, plain clay tiles were hung from battens by small pegs or nails, and each tile has two nibs, or projecting lugs, that hook over the batten. When a peg rots or a nail rusts through, the tile loses its hold and creeps downward until it drops out of its course. Roofers call this nail sickness, and on an old roof it spreads in patches.
The signs are visible from the lane: a tile hanging lower than its neighbours, a gap showing dark felt or boards, or shards of clay in the border bed. Inside, a pale wet patch on the underside of the rafters often appears long before the ceiling stains. Frost can also flake the face of a soft clay tile, and a flaked tile no longer sheds water properly.
What we fix
Where the damage is local, repair is the right answer. We strip only the affected area, keep every tile that is still sound, and fill the gaps with reclaimed or hand-made plain tiles matched for colour and camber. New battens go in beneath, and the tiles are fixed with stainless steel nails or clips, not hung on the old corroded fixings. On very old roofs we may also add a breathable membrane to catch wind-blown rain.
A repair of this kind preserves the character Hart's appraisal describes, and it keeps costs down. A roof that is failing right across the slope is another matter, and we tell you honestly when that point has been reached. Our pitched roofing service describes how a tile repair or re-cover is planned and carried out.